Internally fired tubes for heating furnaces or other purposes



Feb. 18, 1958 J. FALLON v INTERNALLY FIRED TUBES FOR HEATING FURNACES OR OTHER PURPOSES Filed March 10, 1955 JOHN FHLL. ON

United States Patent INTERNALLY FIRED TUBES FOR HEATING FURNACES OR OTHER PURPOSES John Fallon, Smethwick, England Application March 10, 1955, Serial No. 493,521

7 Claims. (Cl. 126-91) This invention has reference to a modification or addition to internally fired tubes for heating furnaces or other purposes as described in the complete specification forming part of the patent application Serial No. 366,781 filed July 8, 1953.

The object of the present invention is to reduce the number of burners and combustion jets required on large furnaces, and to increase the efiiciency and heating capacity of the tubular unit described in the parent specification so as to obtain What may be termed a balanced arrangement of the tubular unit which results in a greater heating efliciency.

The invention consists of an internally fired tubular unit for heating furnaces or other purposes of the kind described and claimed in the parent patent application Serial No. 366,781 filed July 8, 1953, and is characterized by a balanced arrangement of the return tubes of the unit which are supplied with the heating gases from a single combustion chamber through a main inlet tube located coaxial with the outlet of the combustion chamber, exhaust ports being formed in a tubular union connecting the free ends of the main and return tubes.

The invention will now be described with reference to the accompanying drawing in which Fig. 1 is a side elevation of a tubular heat exchange unit for heating furnaces constructed according to the present invention and adapted to be supplied with hot gases of combustion from a suitable jet tube combustion chamber;

Fig. 2 is a side elevational view of a tubular heat exchange unit similar to that in Fig. 1 in which exhaust outlets or ports are formed in the inlet header union adjacent to and extending substantially transversely of each return tube of the unit;

Fig. 3 is a side elevational view of a tubular heat exchange unit similar to that shown in Figs. 1 and 2, provided with exhaust outlets or ports in the return union formed substantially coaxially with each of the return tubes of the unit; and

Fig. 4 is a side elevational view of a tubular heat exchange unit similar to that of Figs. 1, 2 and 3 in which exhaust outlets or ports are formed in the return union adjacent to and substantially transversely of each return tube of the unit.

The illustrated embodiment of this improved heat exchange unit shown in Fig. 1 has a combustion chamber a which is of the jet tube character described in the parent specification. The combustion chamber a has a restricted outlet a mounted within a union b from which centrally extends a main tube 0 of a heat exchange unit in co-axial disposition with the outlet a At its outer end this main tube c is mounted within another tubular union d which unions b and d provide on each side of the main tube 0 connections b and d with parallel return tubes e.

The aforesaid unions b and d are provided with restricted exhaust orifices 1 from which the products of combustion circulating through the tubes 0 and 2 can exhaust to atmosphere or otherwise at a convenient point ice in the circulatory system. In the drawing there is shown three other or alternative positions for the exhaust outlets or ports in Figs. 2, 3, and 4, respectively designated f f and F; the selected disposition of these exhaust outlets depending on the character or type of the furnace or other structure which is required to be heated. Thus a balanced system or balanced flow of the products of combustion obtains in the unit with increased heating surface as compared with the unit described in the parent specification.

The unions b and d may be formed as double or multiple U bends to the centre whereof the main tube 0 is connected; thus an equal divergence of the products of combustion to each return tube is achieved. The Wall of the union against which the products of combustion impinge serves to divert these products equally into each return tube as indicated by the arrows in Fig. 1, and provide for the indicated desired recirculation of some of the cooler gases from tubes 2 through the main tube c, thereby tending to equalize the relative temperatures of the tubes c and e for providing for a longer useful life of the main tube 0 and for a more efiicient utilization of the heat in the products of cumbustion before these are exhausted from the heat exchange unit.

Desirably in any construction of this unit the main supply tube 0 for the combustion gases is located equidistant from a plurality of return or exhaust tubes, these tubes being arranged in parallel with the main inlet tube; that is to say that the inlet tube forms a central tube whereby a balanced system or flow of the products of combustion is obtained.

I claim:

1. An internally fired balanced tubular heat exchange unit for radiantly heated furnaces comprising, in combination, a header union, means forming a combustion chamber exteriorly of said header union and having a jet nozzle communicating therewith, said jet nozzle being provided with an outlet for combustion products and being positioned with said outlet within said union approximately centrally transversely thereof, a main tube having an inlet connected in communication with said header union and extending substantially coaxially of said jet nozzle outlet, a plurality of return tubes positioned axially substantially parallel to said main tube and substantially symmetrically arranged on each side thereof, each of said return tubes having one end thereof connected in communication with said header union and through said header union with said inlet of said main tube providing for recirculation of fluids from said return tubes through said main tube, a second union connecting said main tube with the other ends of each of said return tubes, and one of said unions having separate exhaust ports for respectively exhausting fluid from each of said return tubes, each of said exhaust ports 'being positioned substantially equidistantly from said jet nozzle.

2. An internally fired balanced tubular heat exchange unit for ra-diantly heated furnaces comprising, in combination, a header union, means forming a combustion chamber exteriorly of said header union and having a jet nozzle communicating therewith, said jet nozzle being provided with an outlet for combustion products and being positioned with said outlet within said union approximately centrally transversely thereof, a main tube having an inlet connected in communication with said header union and extending substantially coaxially of said jet nozzle outlet, a plurality of return tubes positioned axially substantially parallel to said main tube and substantially symmetrically arranged on each side thereof, each of said return tubes having one end thereof connected in communication with said header union, and through said header union with said inlet of said main tube providing for recirculation of fluids from said re- 3. turn tubes through said main tube, a second union connecting said main tube with the other ends of each of said return tubes, and one of said unions having separate exhaust ports adjacent to each return tube for respectively exhausting fluid from each of said return tubes, each of said exhaust ports being positioned substantially equidistantly from said jet nozzle.

3. An internally fired balanced tubular unit for radiantly heated furnaces comprising, in combination, a header union, means forming a combination chamber exteriorly of said header union and having a jet nozzle communicating therewith, said jet nozzle being provided with an outlet for combustion products and being positioned with said outlet within said union approximately centrally transversely thereof, a main tube having an inlet connected in communication with said header union and extending substantially coaxially of said jet nozzle outlet, a plurality of return tubes positioned axially substantially parallel to said main tube and substantially symmetrically arranged on each side thereof, each of said return tubes having one end thereof connected in communication with said union and through said header union with said inlet of said main tube providing for recirculation of fluids from said return tubes through said main tube, a second union connecting said main tube with the other ends of each of said return tubes, and said second union having separate exhaust ports in said second union for respectively exhausting fluid from each of said return tubes, each of said exhaust ports being positioned substantially equidistantly from said connection of said second union to said main tube.

4. An internally fired balanced tubular unit for radiantly heated furnaces comprising, in combination, a header union, means forming a combustion chamber having a jet nozzle communicating therewith, said jet nozzle being provided with an outlet for combustion products and being positioned with said outlet within said union approximately centrally transversely thereof, a main tube having an inlet connected in communication with said header union and extending substantially coaxially of said jet nozzle outlet, two return tubes positioned axially substantially parallel to said main tube .and substantially symmetrically arranged on each side thereof, each of said return tubes having one end thereof connected in communication with said union and through said header union with said inlet of said main tube providing for recirculation of fluids from said return tubes through said main tube, a second union connecting said main tube with the other ends of each of said return tubes, each of said unions having a substantially double U-configuration, and one of said unions having separate exhaust ports respectively exhausting fluid from each of said return tubes, each of said exhaust ports being positioned substantially equidistantly from said jet nozzle.

5. An internally fired balanced tubular heat exchange unit for radiantly heated furnaces comprising, in combination, a header union, means forming a combustion chamber having a jet nozzle communicating therewith, said jet nozzle being provided with an outlet for combustion products and being positioned With said outlet within said header union substantially centrally transversely thereof, a main tube having an inlet connected in communication with said header union and extending substantially coaxially of said jet nozzle outlet, a plurality of return tubes extending axially substantially parallel to said main tube and being arranged substantially symmetrically on each side thereof, each of said return tubes having one end thereof connected in communication with said header union and through said header union with said inlet of said main tube providing for recirculation of fluid from said return tubes to said main tube, a second union connecting said main tube with the other ends of each of said return tubes, and one of said unions having separate exhaust ports substantially coaxially with said connections of said return tubes thereto and having a restricted cross-section relative to said return tubes providing for the restricted respective exhausting fluid from each adjacent return tube, each of said exhaust ports being positioned substantially equidistantly from said jet nozzle.

6. An internally fired balanced tubular heat exchange unit for radiantly heated furnaces comprising, in combination, a header union, means forming a combustion chamber having a jet nozzle communicating therewith, said jet nozzle being provided with an outlet for combustion products and being positioned with said outlet within said header union substantially centrally transversely thereof, a main tube having an inlet connected in con1- munication with said header union and extending substantially coaxially of said jet nozzle outlet, a plurality of return tubes extending axially substantially parallel to said main tube and being arranged substantially symmetrically on each side thereof, each of said return tubes having one-end thereof connected in communication With said header union and through said header union with said inlet of said main tube providing for recirculation of fluid from said return tubes to said main tube, a second union connectingsaid main tube with the other ends of each of said return tubes, and separate means forming exhaust ports in said second union substantially coaxially with said connection of said return tubes thereto for respectively exhausting fluid from each of said return tubes, each of said exhaust ports being positioned substantially equidis'tantly from said connection of said second union to said main tube.

7. An internally fired balanced tubular heat exchange unit for radiantly heated furnaces comprising, in combination, a header union, means forming a combustion chamber having a jet nozzle communicating therewith, said jet nozzle being provided with an outlet for combustion products and being positioned with said outlet within said header union substantially centrally transversely thereof, a main tube having an inlet connected in com- 'munication with said header union and extending substantially coaxially of said jet nozzle outlet, a plurality of return tubes extending axially substantially parallel to said main tube and being arranged substantially symmetrically. on each side thereof, each of said return tubes having one end thereof connected in communication with said header union and through said header union with said inlet of said main tube providing for recirculation of fluid from said return tubes to said main tube, a second union connecting said main tube with the other ends of each of said return tubes, and separate means forming exhaust ports in said header union substantially coaxial with the connection of each of said return tubes therewith for respectively exhausting fluid from each of said return tubes, each of said exhaust ports being positioned substantially equidistantly from said connection of said header union with said main tube.

References Cited in the file of this patent UNITED STATES PATENTS 479,769 Thuener et a1 July 26, 1892 1,535,412 Hartfield Apr. 28, 1925 2,424,765 McCollum July 29, 1947 2,465,953 Wollner Mar. 29, 1949 FOREIGN PATENTS 164,491 Great Britain June 9, 1921 716,175 France Oct. 5, 1931 

